Science
Define reflex action. With the help of a flow chart show the path of a reflex action such as sneezing.
Answer
A reflex action is an automatic, quick and involuntary response to a stimulus that does not involve the conscious part of the brain. It helps in protecting the body from harm and occurs through a pathway called the reflex arc.
Example – Reflex action in sneezing :
When dust or an irritant enters the nose, sensory nerves detect it and send signals that cause the muscles of the chest and diaphragm to contract suddenly, forcing air out — this is sneezing, which expels the irritant.
Flow chart showing the path of reflex action (Reflex Arc):
Related Questions
(a) The pH of a sample of tomato juice is 4.6. How is this juice likely to be in taste? Give reason to justify your answer.
(b) How do we differentiate between a strong acid and a weak base in terms of ion-formation in aqueous solutions?
(c) The acid rain can make the survival of aquatic animals difficult. How?
(a) Why is respiratory pigment needed in multicellular organisms with large body size?
(b) Give reasons for the following :
- Rings of cartilage are present in the throat.
- Lungs always contain a residual volume of air.
- The diaphragm flattens and ribs are lifted up when we breathe in.
- Walls of alveoli contain an extensive network of blood vessels.
Study the diagram given below and answer the questions that follow :
(a) Name the defect of vision represented in the diagram. Give reason for your answer.
(b) List two causes of this defect.
(c) With the help of a diagram show how this defect of vision is corrected.
Name and state the rule to determine the direction of a :
(a) magnetic field produced around a current carrying straight conductor.
(b) force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it.